Injection molded synthetic resin component having a wood veneer outer layer

ABSTRACT

A composite molded article is formed by forming a composite wood overlay surface material by laminating a wood veneer on a front side of a base sheet selected from one of a metal sheet and a resin sheet; laminating a back sheet selected from one of a porous material and a fibrous material on a back side of said base sheet; coating said wood veneer incorporated in said composite wood overlay surface material; placing said composite wood overlay surface material in a mold; and injecting a resin onto said back sheet incorporated in said composite wood overlay surface material. Thus, the composite molded article has an excellent appearance of coating on the surface of the article.

This is a division of application Ser. No. 07/941,734, filed Sep. 8,1992, now U.S. Pat. No. 5,264,062.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to production methods for a compositemolded article comprising a composite wood overlay surface material anda synthetic resin. The production method of a composite molded articleaccording to the present invention provides an excellent appearance ofcoating on the composite molded article by the production steps of firstcoating a wood veneer included in the composite wood overlay surfacematerial, and then injecting the synthetic resin.

2. Description of the Related Art

Composite molded articles having grain patterns comprising a compositewood overlay surface material and a synthetic resin have been usedwidely in the interiors of cars, for furniture, and for electricappliances.

In order to produce composite molded articles having wood grainpatterns, a composite wood sheet (such as a wood veneer backed by asliced wooden veneer, a plywood, an unwoven fabric, or the like) as asurface material, has been employed in a production method comprisingthe steps of placing the surface material in a mold, injection-moldingthereinto a synthetic resin which is to be a core material, and thencoating the surface material.

The composite molded articles produced according to the aforementionedmethod are superior in appearance. However, when the form of thecomposite molded articles is complicated, inferior units are oftenproduced due to the cracking of the surface material of the compositewood sheet.

In order to avoid the production of such inferior units, a conventionalmethod developed includes a step of placing, in a mold, a surfacematerial composed of an aluminum sheet laminated on the back of the woodveneer. According to this method, the products have beautiful grainpatterns and the production of inferior units can be avoided since thewood veneer is backed by the aluminum sheet. However, this methodrequires time and labor because the step of finish-coating on the curvedsurface of the composite molded article is not easily adapted toautomation of the coating step.

SUMMARY OF THE INVENTION

The object of the present invention is to provide production methods fora composite molded article comprising a composite wood overlay surfacematerial and a synthetic resin, having an excellent appearance ofcoating on the surface of the composite molded article, by coating aflat surface of the composite wood overlay surface material beforemolding; therefore, automation of the coating step is possible.

The aforementioned object is achieved by the steps of: coating the woodveneer composing the composite wood overlay surface material (thecoating step may include the sub-steps of, for example, a preparatorytreatment, a bottom coating application, one or more middle coatingapplications, and an upper coating application); placing the compositewood overlay surface material in the mold; and injection-molding thesynthetic resin thereinto.

According to the present invention, there is provided a productionmethod for a composite molded article, the method comprising the stepsof:

forming a composite wood overlay surface material by laminating a woodveneer on a front side of a base sheet selected from one of a metalsheet and a resin sheet; laminating a back sheet selected from one of aporous material and a fibrous material on a back side of said basesheet;

coating said wood veneer incorporated in said composite wood overlaysurface material;

placing said composite wood overlay surface material in a mold; and

injecting a resin onto said back sheet incorporated in said compositewood overlay surface material.

The production method of a composite molded article according to thepresent invention enables the coating of a flat surface of the compositewood overlay surface material before molding, and accordingly, anexcellent appearance of coating can be obtained, and the automation ofthe coating step is possible. Furthermore, when an open-pore treatmentis carried out, the appearance of the thus-treated composite moldedarticle of the present invention is superior to that of anopen-more-treated article by an ordinary method of applying coating,since the surface of the wood veneer is pressed against the mold bypressure from the injection-molding, and therefore, a smooth texture ofthe surface and a sharp appearance of the wood Grain are obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a composite wood overlay surface material.

FIG. 2 is a sectional view of a composite molded article formed byinjecting a synthetic resign in a mold for injection-molding.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a composite wood overlay surface material 1 which is anintegrated sheet composed of a metal sheet 3 or a resin sheet 4, oneside of which is laminated on a wood veneer 2, and the other side ofwhich is laminated on a porous material 5 or fibrous material 6.

The metal sheet 3 may be of aluminum, steel, or copper, and may beformed as a sheet with a thickness between 0.01 and 0.5 mm. It isparticularly preferred that the thickness of the metal sheet 3 bebetween 0.1 and 0.3 mm. Also, it is preferred that the metal sheet 3 bechemically pretreated in order to enhance its corrosion resistance andadhesion. A resin sheet 4 may be used in place of the metal sheet 3depending on the use of the composite wood overlay surface material. Theresin sheet may be of thermoplastic or thermosetting resin, or of anyother type of resin.

The material for the wood veneer 2 is not specified, however, a woodhaving a beautiful grain pattern is desirable. The thickness of the woodveneer 2 may preferably be between 0.15 and 0.5 mm, and morespecifically, may be approximately 0.2 mm.

A wood veneer or a foam resin plate may be used as a porous material 5.The thickness of the porous material 5 must be in a range where thecomposite wood overlay surface material 1 can be appropriately shaped;however, the thickness of the porous material 5 is not specificallylimited.

A fibrous material 6 may be used in place of the porous material 5. Anon-woven fabric, a paper, or a glass-fiber mat may be used as thefibrous material 6. The thickness of the fibrous material 6 must be in arange where the composite wood overlay surface material 1 can beappropriately shaped; however, the thickness of the porous material 5 isnot specifically limited. It is preferred that the weight per unit areaof the fibrous material 6 be from 30 to 70 g/m².

The components of the composite wood overlay surface material, namelythe wood veneer 2, metal sheet 3 (or resin sheet 4 in place of the metalsheet 3), and porous material 5 (or fibrous material 6 in place ofporous material 5), are combined by using an adhesive agent in order toform a composite wood overlay surface material. The adhesive agent isnot specifically limited, however, since a molten synthetic resin isinjection-molded on the composite wood overlay surface material 1 in alater process, it is preferred that a heat-resistant thermosettingadhesive agent such as an epoxy or urethane adhesive agent be applied sothat the composite wood overlay surface material 1 will not bedeteriorated by heat; and it is preferred that after applying theadhesive agent, the components of the composite wood overlay surfacematerial be bonded together by pressing and heating.

Subsequently, the wood veneer 2, included in the thus-obtained compositewood overlay surface material 1, is coated. The method for coating isnot specifically limited; however the process of coating may include thesteps of ground-polishing, wash-coating, stain-coating, priming,polishing, bottom-coating, middle-coating, upper-coating, and polishing.A material for coating may be any coating material conventionally usedfor coating wood, such as a cellulose-based, an acryl-based, apolyurethane-based, a melamine-based, an alkyd-based, and an unsaturatedpolyester-based coating. A powder coating using a powdered epoxy-basedcoating and the like may be carried out. It is preferred that open-poretreatment be carried out, wherein the primer coating is not applied inorder to retain the excellent appearance of the natural wood patterns.

Subsequently, the thus-coated composite wood overlay surface material 1is placed in a mold for injection-molding, and a synthetic resin 7 suchas polypropylene or an ABS resin is injected thereinto. Accordingly, thecomposite wood overlay surface material 1 is molded along the shape ofthe mold in order to obtain a desired shape, and at the same time, thecomposite wood overlay surface material 1 and the synthetic resin 7 arecombined to form a unitary body of a molded article. By releasing thismolded article from the mold, a composite molded article 8 as shown inFIG. 2 is obtained. Further overcoating may be carried out aftermolding.

According to the present invention, a composite molded article 8 mayalso be obtained by coating the composite wood overlay surface material1, preliminarily molding (forming) the composite wood overlay surfacematerial, placing the composite wood overlay surface material 1 in themold for injection-molding, and injection-molding the synthetic resin 7thereinto. In the preliminary molding, the parts on the composite woodoverlay surface material, whereof the shape is changed largely bymolding, is preliminarily molded by a method such as press working.

By coating a flat surface of the wood veneer 2 (included in thecomposite wood overlay surface material 1), the above-describedproduction methods allow the automation of the coating process and allowefficient production. Furthermore, when an open-pore treatment iscarried out, the appearance of the thus-treated composite molded articleof the present invention is superior to that of an open-pore-treatedarticle by an ordinary method of applying coating, since the surface ofthe wood veneer is pressed against the mold by pressure from theinjection-molding, and therefore, a smooth texture of the surface and asharp appearance of vessels are obtained. Furthermore, the productionmethod wherein the composite wood overlay surface material ispreliminarily molded allows the production of a composite molded article8 having a complex shape.

EXAMPLE

A composite wood overlay surface material 1, having three layers, wasformed by combining a wood veneer (whereof the thickness is 0.2 mm) oneach of the front side and the back side of a chemically pretreatedaluminum sheet (whereof the thickness is 0.3 mm), as a metal sheet 3, byusing an adhesive agent so as to form a unitary body; the wood veneer onthe front side was used as a wood veneer 2, and the wood veneer on theback side was used as a porous material 5.

A crosslinkable urethane dispersion adhesive agent was used as theadhesive agent. An open-pore coating (thin coating) application wascarried out on a surface of the wood veneer 2 situated on the front sideof the composite wood overlay surface material 1 by an open-pore coatingmethod. For the open-pore coating, a preparatory treatment was performedby polishing with sandpaper (#240), coloring was applied by wiping usinga colored urethane resin, and an undercoating was applied using aurethane clear paint.

The composite wood overlay surface material 1 was placed in a mold forinjection-molding, and an ABS resin was injected thereinto and a moldedarticle was formed. In the thus-obtained molded article, the compositewood overlay surface material 1 and the resin 7 form a unitary body. Asmooth texture of the surface and a sharp appearance of wood grain areobtained since the surface of the wood veneer is pressed against themold by pressure during the injection-molding.

What is claimed is:
 1. A composite molded article comprising:a) asynthetic resin component having a front surface; and b) a wood overlaycomponent including:1) a base sheet having front and rear surfaces; 2) awood layer; 3) a back layer formed of a material selected from the groupconsisting of a non-woven fabric, a paper, a glass-fiber mat and a foamresin; and 4) an adhesive located between said base sheet and said woodlayer and between said base sheet and said back layer for securing saidwood layer to said front surface of said base sheet and said back layerto said rear surface of said base sheet; whereina portion of said frontsurface of said synthetic resin component penetrates into said backlayer of said base sheet for securing said synthetic resin component tosaid wood overlay component to form a unitary structure.
 2. A compositemolded article according to claim 1, wherein said base sheet comprises ametal.
 3. A composite molded article according to claim 1, wherein saidbase sheet is constructed of a resin.
 4. A composite molded articleaccording to claim 2, wherein said metal is selected from the groupconsisting of aluminum, steel, and copper.
 5. A composite molded articleaccording to claim 1, wherein said back layer is formed of a foam resin.6. A composite molded article according to claim 1, wherein the materialselected form the group consisting of a non-woven fabric, a paper and aglass-fiber mat has a weight per unit area of 30 to 70 g/m².
 7. Thecomposite molded article of claim 1, wherein said said synthetic resincomponent comprises an injection molded material.
 8. The compositemolded article of claim 1, wherein the synthetic resin component isformed of an injection molded material and said wood overlay componentis molded prior to said synthetic resin component being injectionmolded.
 9. A composite molded article comprising:a) a synthetic resincomponent; and b) a wood overlay component including:1) a base sheetformed of a material selected from the group consisting of a polymericresin and a metal sheet having front and rear surfaces; 2) a wood veneerlayer attached to the front surface of the base sheet; and 3) a backlayer formed of a material selected from the group consisting of anon-woven fabric, a paper, a glass-fiber mat and a foam resin, said backlayer being attached to the rear surface of the base sheet; whereinsaidsynthetic resin component comprises a synthetic resin material which isinjection molded onto the back layer.
 10. A composite molded articleaccording to claim 9, wherein said metal is selected from the groupconsisting of aluminum, steel, and copper.
 11. A composite moldedarticle according to claim 9, wherein said back layer is formed of afoam resin.
 12. A composite molded article according to claim 9, whereinthe material selected form the group consisting of a non-woven fabric, apaper and a glass-fiber mat has a weight per unit area of 30 to 70 g/m².13. The composite molded article of claim 9, wherein said syntheticresin component is formed of an injection molded material and said woodoverlay component is molded prior to the synthetic resin being injectionmolded.